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| author | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2024-01-16 16:27:02 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2024-01-16 17:12:48 +0000 |
| commit | db4e496aadf1d7ab1c5af24410394d1551ddd3f0 (patch) | |
| tree | 9c70c875e87e53441175b90183c15b7154e9004e | |
| parent | 4bd09ce06f50d266c992c984cc993384d5e6655e (diff) | |
| download | gcc-db4e496aadf1d7ab1c5af24410394d1551ddd3f0.zip gcc-db4e496aadf1d7ab1c5af24410394d1551ddd3f0.tar.gz gcc-db4e496aadf1d7ab1c5af24410394d1551ddd3f0.tar.bz2 | |
AArch64: Reassociate CONST in address expressions
GCC tends to optimistically create CONST of globals with an immediate offset.
However it is almost always better to CSE addresses of globals and add immediate
offsets separately (the offset could be merged later in single-use cases).
Splitting CONST expressions with an index in aarch64_legitimize_address fixes
part of PR112573.
gcc/ChangeLog:
PR target/112573
* config/aarch64/aarch64.cc (aarch64_legitimize_address): Reassociate
badly formed CONST expressions.
gcc/testsuite/ChangeLog:
PR target/112573
* gcc.target/aarch64/pr112573.c: Add new test.
| -rw-r--r-- | gcc/config/aarch64/aarch64.cc | 11 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/aarch64/pr112573.c | 15 |
2 files changed, 26 insertions, 0 deletions
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index 7d1f8c6..e6bd3fd 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -12617,6 +12617,17 @@ aarch64_legitimize_address (rtx x, rtx /* orig_x */, machine_mode mode) not to split a CONST for some forms of address expression, otherwise it will generate sub-optimal code. */ + /* First split X + CONST (base, offset) into (base + X) + offset. */ + if (GET_CODE (x) == PLUS && GET_CODE (XEXP (x, 1)) == CONST) + { + poly_int64 offset; + rtx base = strip_offset (XEXP (x, 1), &offset); + + base = expand_binop (Pmode, add_optab, base, XEXP (x, 0), + NULL_RTX, true, OPTAB_DIRECT); + x = plus_constant (Pmode, base, offset); + } + if (GET_CODE (x) == PLUS && CONST_INT_P (XEXP (x, 1))) { rtx base = XEXP (x, 0); diff --git a/gcc/testsuite/gcc.target/aarch64/pr112573.c b/gcc/testsuite/gcc.target/aarch64/pr112573.c new file mode 100644 index 0000000..be04c0c --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/pr112573.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-section-anchors" } */ + +char a[100]; + +void f1 (int x, int y) +{ + *((a + y) + 3) = x; + *((a + y) + 2) = x; + *((a + y) + 1) = x; + *((a + y) + 0) = x; +} + +/* { dg-final { scan-assembler-times "strb" 4 } } */ +/* { dg-final { scan-assembler-times "adrp" 1 } } */ |